Vehicle-to-vehicle (V2V) communications enable a wide range of vehicle active safety applications provided in an effort to help reduce traffic accidents. An important category of such applications, known to be highly effective in reducing head-on collisions, is Emergency Electronic Brake Lights (EEBL). When a vehicle performs an emergency braking maneuver generally defined as a deceleration rate exceeding a predefined value, an EEBL application on the decelerating vehicle sends EEBL messages to nearby vehicles so that they can assess collision risks and warn their drivers or take other action as may be necessary or desired. EEBL messages can be disseminated through V2V communications to reach vehicles whose drivers' line of sight to the braking vehicle is obstructed by other vehicles or bad weather conditions. This has been shown to be particularly useful in helping drivers avoid head-on collisions.
However, adversaries can compromise vehicles' communication systems or manipulate the input data to a vehicle's EEBL application to cause a vehicle to send false EEBL messages using the vehicle's valid security credentials or by other means. For example, a malicious software or hardware with access to the vehicle's Car Area Network (CAN) can send fictitious braking status and vehicle position information to the EEBL application to cause it to send EEBL messages when the vehicle is in fact not braking or when the vehicle is not braking above a threshold deceleration rate suggestive of an emergency or panic stop maneuver. This can cause nearby drivers to make abrupt maneuverers that can significantly increase traffic accidents. Therefore, an important factor for making EEBL applications deployable is an ability to detect false EEBL messages or, in other words, to determine the trustworthiness of the received EEBL messages.